Not that many decades ago, Santo Domingo didn't used to have a traffic jam problem. Look at it now. Reminds me when people say the economic growth isn't "seen," because apparently Santo Domingo is like Havana which despite all these decades and having a population in the millions, traffic jams are still unknown. That's what happen when an economic growth isn't seen. No money to get more cars.
On the other hand, San Juan in Puerto Rico does gets traffic jams too.